In a synthetic aperture radar apparatus disclosed by Patent Literature 1 listed below, in order to make it possible to discriminate between a pulse signal emitted from an SAR sensor at a desired observation point and a pulse signal emitted from the SAR sensor at another observation point other than the desired observation point, the chirp of a pulse signal to be emitted into space is changed (switching between up-chirp and down-chirp is performed).
This makes it possible to reduce unavoidable range ambiguity in synthetic aperture observations.